The present invention relates to an endodontic stabilizer for insertion into the jawbone of the patient's mouth through an aperture in a loose tooth to stabilize the tooth, and more specifically to threaded, self-tapping endodontic stabilizers.
The efficacy of an endodontic stabilizer depends essentially upon three considerations. First, the stabilizer should form an effective apical seal (that is, the seal between the stabilizer and the base of the tooth defining the aperture). Second, the stabilizer must be effectively retained within the tooth to fix the tooth relative to the stabilizer. Third, the stabilizer must be effectively retained within the jawbone beyond the apex to fix the stabilizer relative to the jawbone.
Two types of endodontic stabilizers are currently used in clinical practice -- smooth, tapered stabilizers and threaded, self-tapping stabilizers. With smooth, tapered stabilizers, formation of the apical seal is dependent upon effective wedging of the cemented implant at the apex, resistance to implant withdrawal from the tooth is dependent upon the shearing properties of the dental cement employed, and stabilizer retention within the jawbone is dependent upon the formation of collagenous perio-stabilizer ligament about the stabilizer. The smooth, tapered stabilizers have been found to be deficient in all three areas of consideration.
The threaded, self-tapping endodontic stabilizers utilize threads of very low pitch to minimize the torque required for insertion into the tooth dentin during the tapping process. Accordingly, the threads typically define lands of V-shaped cross-section and little, if any, intervening groove area. Such stabilizers thread a portion of the tooth proximal to the apical foramen, and thus provides both a positive apical seal and great resistance to withdrawal forces from the tooth. Indeed, when a tooth specimen has a threaded self-tapping stabilizer properly placed and then removed, examination of the internal surface of the canal will reveal threads in the dentin. Thus threaded, self-tapping stabilizers rate high in the first two areas of consideration (apical seal and retention within the tooth); however they provide little, if any, improvement over the smooth tapered stabilizers when it comes to the third consideration (i.e. the retention of the stabilizer within the jawbone beyond the apex). Generation of perio-stabilizer collagenous ligament adjacent the threads of the stabilizer is minimal, and in fact the ligament over a period of time tends to withdraw from the threaded surface of the stabilizer.
Additional complications occur where the tooth is not only loose, but also broken off coronally, so that an artificial crown must be secured to the stump of the stabilized tooth. Conventional practice in this instance is to use a smooth, tapered stabilizer, and then break off and then remove the upper segment of the stabilizer, leaving the bottom segment to stabilize the tooth. A gold post (sometimes threaded, sometimes unthreaded) is then cemented on the upper portion of the stub above the truncated stabilizer, the upper portion of the gold post serving as a base or secural point for the artificial crown. This procedure has several drawbacks including poor retention of the gold post within the tooth, the extra expense of a gold post, and the extra labor required for breaking of the stabilizer and insertion of the gold post.
Accordingly, it is an object of the present invention to provide a threaded, self-tapping endodontic stabilizer affording a high degree of stabilizer retention within the jawbone beyond the apex.
Another object is to provide such a stabilizer which combines a high degree of retention within the jawbone with an effective apical seal and effective retention within the tooth.
A further object is to provide such a stabilizer for use with a broken tooth, the stabilizer having a head which is adapted to receive an artificial crown thereon.